Defects in operating machines often result in the machine producing increased vibrations at certain frequencies. For example, a rotating gear with a cracked tooth will produce an increased amount of vibration every time the cracked tooth comes into contact with an associated gear. It is well known that these vibrations tend to be detectable long before the machinery defect becomes serious enough to cause the machine to malfunction. Therefore, vibrations produced by operating machines are measured in order to detect machinery defects before they cause a failure.
Typically, vibration data collectors and analyzers are used to take vibration measurements from operating machines and analyze the vibration measurements to determine if a machinery defect is likely to be present. The process of performing periodic predictive maintenance surveys on plant equipment is a manual process that involves a technician carrying a vibration analyzer to each measurement point and affixing a probe to the measurement point to measure vibration data and other types of dynamic signals and process variables. This process often involves anywhere from ten seconds to several minutes at each measurement location. Because industrial plants often have large amounts of machinery, performing these measurements becomes a time consuming task. In a single 8-hour shift, a technician could spend no more than 30 seconds for each measurement if his total measurement route included 1000 locations. Thus, in order to cover large populations of equipment in a cost effective manner, there is a need to minimize the amount of time spent at each measurement location. However, this need to minimize the amount of time spent collecting data is at odds with the need to get the full complement of measurements required to provide optimal detection and diagnosis of machine faults. To reliably detect machinery faults, it is often desirable to measure several parameters such as an overall vibration reading, multiple vibration spectra with differing engineering units and/or band widths, and a vibration spectrum produced by an enveloping process. These and other measurements may be needed at any given measurement location in order to detect the fault modes characteristic to the machinery being monitored. These multiple measurements impose a heavy time burden on the technician performing the measurements.
Analyzers with two or more parallel processing channels have been available for some time. One such prior art device is the CSI 2120 analyzer which is described in U.S. Pat. No. 5,633,811. In general, these types of portable analyzers were introduced to enable a technician to take measurements from several sensors simultaneously. Typically, the independent sensors are positioned with different spatial orientations with respect to the machine being monitored, such as horizontally, vertically, and axially. Each sensor has an associated processing channel that processes the signal produced by it. This approach may reduce the amount of time required to collect a set of measurements if the analyzer has been designed with sufficient processing power. However, the disadvantage of this approach is that the technician performing the tests has to manage the task of handling multiple sensors and insuring that the correct sensor is in the correct measurement location. Insuring proper sensor placement involves a considerable amount of time and effort and, thus, minimizes the time savings realized from using multiple sensors with multiple processing paths. In addition, the likelihood of taking an erroneous measurement is significantly increased by the increased complexity.